High-density lipoprotein-associated paraoxonase-1 activity for prediction of adverse outcomes in outpatients with chronic heart failure

Paraoxonases at the Heart of Neurological Disorders

Paraoxonase enzymes serve as an important physiological redox system that participates in the protection against cellular injury caused by oxidative stress. The PON enzymes family consists of three members (PON-1, PON-2, and PON-3) that share a similar structure and location as a cluster on human chromosome 7. These enzymes exhibit anti-inflammatory and antioxidant properties with well-described roles in preventing cardiovascular disease. Perturbations in PON enzyme levels and their activity have also been linked with the development and progression of many neurological disorders and neurodegenerative diseases. The current review summarizes the available evidence on the role of PONs in these diseases and their ability to modify risk factors for neurological disorders. We present the current findings on the role of PONs in Alzheimer's disease, Parkinson's disease, and other neurodegenerative and neurological diseases.

Novel Oxidative Stress Biomarkers with Risk Prognosis Values in Heart Failure

Oxidative stress (OS) is mediated by reactive oxygen species (ROS), which in cardiovascular and other disease states, damage DNA, lipids, proteins, other cellular and extra-cellular components. OS is both initiated by, and triggers inflammation, cardiomyocyte apoptosis, matrix remodeling, myocardial fibrosis, and neurohumoral activation. These have been linked to the development of heart failure (HF). Circulating biomarkers generated by OS offer potential utility in patient management and therapeutic targeting. Novel OS-related biomarkers such as NADPH oxidases (sNox2-dp, Nrf2), advanced glycation end-products (AGE), and myeloperoxidase (MPO), are signaling molecules reflecting pathobiological changes in HF. This review aims to evaluate current OS-related biomarkers and their associations with clinical outcomes and to highlight those with greatest promise in diagnosis, risk stratification and therapeutic targeting in HF.

Association of Paraoxonase-1 and NT-proBNP with Clinical, Clinico-Pathologic and Echocardiographic Variables in Dogs with Mitral Valve Disease

The objective of the present study was to measure the concentration of Paraoxonase-1 (PON-1) and N-terminal-prohormone-B-type natriuretic peptide (NT-proBNP), in the serum of dogs with degenerative Mitral Valve Disease (MVD), in order to identify their association with the clinical stage and specific clinico-pathologic and echocardiographic findings.Eighty dogs diagnosed with MVD and staged according to the ACVIM (American College of Veterinary Internal Medicine) consensus statement (B1, B2, C and D), based on their clinical, radiographic, and echocardiographic findings, were included in the study. NT-proBNP was measured only in stage B1 and B2 dogs. Clinical stage did not have a significant effect on PON-1 concentrations (p = 0.149), but NT-proBNP levels were lower in B1 dogs (p = 0.001). A significant correlation between PON-1 and total plasma proteins (p = 0.001), albumin (p = 0.003) and white blood cell count (p = 0.041) was detected, whereas there was no significant correlation (p = 0.847) between PON-1 and NT-proBNP concentrations. PON-1 showed a significant but weak negative correlation with normalized left ventricular internal diameter at diastole (LVIDdn) (p = 0.022) and systole (LVIDsn) (p = 0.012), as well as mitral valve E to A wave velocity ratio (MV E/A) (p = 0.015), but not with Left Atrial to Aortic root ratio (LA/Ao) (p = 0.892) or fractional shortening (FS%) (p = 0.944). PON-1 seems to be an insensitive marker of clinical stage and disease severity in MVD, but can be indicative of some clinico-pathological and echocardiographic changes. NT-proBNP changes are independent of oxidative stress.

Cardioprotective Role for Paraoxonase-1 in Chronic Kidney Disease

Paraoxonase-1 (PON-1) is a hydrolytic enzyme associated with HDL, contributing to its anti-inflammatory, antioxidant, and anti-atherogenic properties. Deficiencies in PON-1 activity result in oxidative stress and detrimental clinical outcomes in the context of chronic kidney disease (CKD). However, it is unclear if a decrease in PON-1 activity is mechanistically linked to adverse cardiovascular events in CKD. We investigated the hypothesis that PON-1 is cardioprotective in a Dahl salt-sensitive model of hypertensive renal disease. Experiments were performed on control Dahl salt-sensitive rats (SSMcwi, hereafter designated SS-WT rats) and mutant PON-1 rats (SS-Pon1em1Mcwi, hereafter designated SS-PON-1 KO rats) generated using CRISPR gene editing technology. Age-matched 10-week-old SS and SS-PON-1 KO male rats were maintained on high-salt diets (8% NaCl) for five weeks to induce hypertensive renal disease. Echocardiography showed that SS-PON-1 KO rats but not SS-WT rats developed compensated left ventricular hypertrophy after only 4 weeks on the high-salt diet. RT-PCR analysis demonstrated a significant increase in the expression of genes linked to cardiac hypertrophy, inflammation, and fibrosis, as well as a significant decrease in genes essential to left ventricular function in SS-PON-1 KO rats compared to SS-WT rats. A histological examination also revealed a significant increase in cardiac fibrosis and immune cell infiltration in SS-PON-1 KO rats, consistent with their cardiac hypertrophy phenotype. Our data suggest that a loss of PON-1 in the salt-sensitive hypertensive model of CKD leads to increased cardiac inflammation and fibrosis as well as a molecular and functional cardiac phenotype consistent with compensated left ventricular hypertrophy.

Effect of supplementation with polyphenol extract of Thymus atlanticus on paraoxonase-1 activity, insulin resistance, and lipid profile in high-fat diet-fed hamsters

Thymus atlanticus has been used by Moroccan people to treat a variety of health problems, particularly metabolic disorders. In this study, hamsters fed a high-fat diet daily received distilled water (a positive control) or a single dose of Thymus atlanticus polyphenols (Pp) for 63 days. The negative control was fed a normal diet and received distilled water. Results showed that the supplementation of HFD with Pp significantly (p < .001) reduced the levels of MDA and LDL cholesterol, restored insulin level, and increased the activities of serum paraoxonase-1 and HDL cholesterol levels, but did not affect (p > .05) the activity of superoxide dismutase and glutathione peroxidase when compared with the group feeding HFD alone. Thymus atlanticus could be an effective agent against dyslipidemia, oxidative stress, and insulin resistance. PRACTICAL APPLICATIONS: HFD consumption is a risk factor for oxidative stress and the development of metabolic disorders, such as hyperlipidemia and insulin resistance, which may result in atherosclerosis and related cardiovascular diseases, the leading causes of death globally. The management of these alterations is an important strategy to prevent and treat heart complications. Our results showed thatT. atlanticus effectively alleviated HFD-induced hyperlipidemia and insulin resistance and improved PON1 activity. T. atlanticus is a source of biomolecules that may be an effective supplement for controlling HFD-related metabolic disorders. Therefore, the findings of this study may be helpful in the preparation of effective supplements from T. atlanticus to control metabolic disorders and related complications.

Paraoxonase-1 Activity in Breast Cancer Patients Treated With Doxorubicin With or Without Trastuzumab

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PON-1 is an HDL-associated cardioprotective enzyme that prevents oxidized-LDL formation and has not previously been studied in cardio-oncology.

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To determine the associations between PON-1 and the development of CTRCD, the Pon and Aryl serum enzymatic activity levels of PON-1 were quantified in a cohort of 225 patients with breast cancer receiving doxorubicin with or without trastuzumab.

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After doxorubicin completion, the activity levels of both Pon and Aryl were significantly decreased.

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Early increases in the Pon enzymatic activity of PON-1 were associated with increased risk of CTRCD.

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With further study, PON-1 activity may provide insight into mechanistic risk prediction of CTRCD with doxorubicin chemotherapy.

The objective of this study was to determine associations of paraoxonase-1 (PON-1) with development of cancer therapy–related cardiac dysfunction (CTRCD). PON-1 is a cardioprotective enzyme associated with high-density lipoprotein that prevents oxidized low-density lipoprotein formation. Given the role of oxidative stress in doxorubicin-induced cardiotoxicity, PON-1 activity may have relevance for the prediction of CTRCD. In 225 patients with breast cancer receiving doxorubicin with or without trastuzumab, we quantified PON-1 activity through its paraoxonase (Pon) and arylesterase (Aryl) enzymatic activity at baseline, during, and after doxorubicin completion. Echocardiograms were performed at baseline, during therapy, and annually. CTRCD was defined as a decrease in left ventricular ejection fraction by ≥10% from baseline to <50%. Associations between baseline biomarkers and clinical variables were determined using multivariable linear regression. Associations between changes in biomarker activity and time to CTRCD were evaluated using Cox regression. Pon was directly associated with Black race and inversely associated with Stage 2 cancer. Aryl was inversely associated with body mass index. After doxorubicin completion, activity levels of Pon and Aryl were significantly decreased (median ratio compared with baseline for Pon: 0.95 [Q1-Q3: 0.81-1.07, P < 0.001]; for Aryl: 0.97 [Q1-Q3: 0.85-1.08, P = 0.010]). A total of 184 patients had an available quantitated echocardiogram at baseline and at least 1 follow-up visit. Increases from baseline in Pon at doxorubicin completion were independently associated with increased CTRCD risk (per 10% increase: hazard ratio [HR]: 1.21; 95% confidence interval [CI]: 1.05-1.39; P = 0.007). Associations between increases in Aryl and CTRCD tended in the same direction but were of borderline statistical significance (HR: 1.17; 95% CI: 0.99-1.38; P = 0.071). In patients with breast cancer treated with doxorubicin with or without trastuzumab, increases in the Pon enzymatic activity level of PON-1 were associated with increased CTRCD risk. PON-1 activity may be relevant to mechanistic risk prediction of cardiotoxicity with anthracyclines.

The Increase in Paraoxonase 1 Is Associated With Decrease in Left Ventricular Volume in Kidney Transplant Recipients

Background: Patients on dialysis have impaired cardiac function, in part due to increased fluid volume and ventricular stress. Restored kidney function through transplantation reduces left ventricular volume in both systole and diastole. We previously reported that the decrease in NT-proB-type natriuretic peptide (NT-proBNP) was associated with a decrease in adiponectin. Paraoxonase 1 (PON1) has been inversely associated with cardiovascular outcomes. We now report the association of changes in PON1 with changes in left ventricular volume and left ventricular mass after kidney transplantation.

Design: Patients on dialysis were assessed at baseline and 12 months after kidney transplantation (n = 38). A comparison group of patients on dialysis who were not expected to receive a transplant in the next 24 months were studied (n = 43) to determine if the change of PON1 with kidney transplantation achieved a significance greater than that due to biologic variation. Left ventricular volume and mass were determined by cardiac magnetic resonance imaging. PON1 was measured by arylesterase activity and by mass.

Results: PON1 mass and activity were not different between the groups at baseline. Both PON1 mass and activity were increased post-kidney transplantation (p < 0.0001 for change). The change in PON1 mass (p = 0.0062) and PON1 arylesterase activity (p = 0.0254) were inversely correlated with the change in NT-proBNP for patients receiving a kidney transplant. However, only the change in the PON1 mass, and not the change in PON1 arylesterase, was inversely correlated with the change in left ventricular volume (ml/m2.7) (p = 0.0146 and 0.0114 for diastolic and systolic, respectively) and with the change in hemoglobin (p = 0.0042).

Conclusion: Both PON1 mass and arylesterase activity are increased by kidney transplantation. The increase in PON1 mass is consistent with a novel relationship to the increase in hemoglobin and decrease in left ventricular volume and NT-proBNP seen when kidney function is restored.

Impaired High-Density Lipoprotein Function in Patients With Heart Failure

Background

We recently showed that, in patients with heart failure, lower high‐density lipoprotein (HDL) cholesterol concentration was a strong predictor of death or hospitalization for heart failure. In a follow‐up study, we suggested that this association could be partly explained by HDL proteome composition. However, whether the emerging concept of HDL function contributes to the prognosis of patients with heart failure has not been addressed.

Methods and Results

We measured 3 key protective HDL function metrics, namely, cholesterol efflux, antioxidative capacity, and anti‐inflammatory capacity, at baseline and after 9 months in 446 randomly selected patients with heart failure from BIOSTAT‐CHF (A Systems Biology Study to Tailored Treatment in Chronic Heart Failure). Additionally, the relationship between HDL functionality and HDL proteome composition was determined in 86 patients with heart failure. From baseline to 9 months, HDL cholesterol concentrations were unchanged, but HDL cholesterol efflux and anti‐inflammatory capacity declined (both P<0.001). In contrast, antioxidative capacity increased (P<0.001). Higher HDL cholesterol efflux was associated with lower mortality after adjusting for BIOSTAT‐CHF risk models and log HDL cholesterol (hazard ratio, 0.81; 95% CI, 0.71–0.92; P=0.001). Other functionality measures were not associated with outcome. Several HDL proteins correlated with HDL functionality, mainly with cholesterol efflux. Apolipoprotein A1 emerged as the main protein associated with all 3 HDL functionality measures.

Conclusions

Better HDL cholesterol efflux at baseline was associated with lower mortality during follow‐up, independent of HDL cholesterol. HDL cholesterol efflux and anti‐inflammatory capacity declined during follow‐up in patients with heart failure. Measures of HDL function may provide clinical information in addition to HDL cholesterol concentration in patients with heart failure.

Multiplexed measurement of candidate blood protein biomarkers of heart failure

AIMS

There is a critical need for better biomarkers so that heart failure can be diagnosed at an earlier stage and with greater accuracy. The purpose of this study was to design a robust mass spectrometry (MS)-based assay for the simultaneous measurement of a panel of 35 candidate protein biomarkers of heart failure, in blood. The overall aim was to evaluate the potential clinical utility of this biomarker panel for prediction of heart failure in a cohort of 500 patients.

METHODS AND RESULTS

Multiple reaction monitoring (MRM) MS assays were designed with Skyline and Spectrum Mill PeptideSelector software and developed using nanoflow reverse phase C18 chromatographic Chip Cube-based separation, coupled to a 6460 triple quadrupole mass spectrometer. Optimized MRM assays were applied, in a sample-blinded manner, to serum samples from a cohort of 500 patients with heart failure and non-heart failure (non-HF) controls who had cardiovascular risk factors. Both heart failure with reduced ejection fraction (HFrEF) patients and heart failure with preserved ejection fraction (HFpEF) patients were included in the study. Peptides for the Apolipoprotein AI (APOA1) protein were the most significantly differentially expressed between non-HF and heart failure patients (P = 0.013 and P = 0.046). Four proteins were significantly differentially expressed between non-HF and the specific subtypes of HF (HFrEF and HFpEF); Leucine-rich-alpha-2-glycoprotein (LRG1, P < 0.001), zinc-alpha-2-glycoprotein (P = 0.005), serum paraoxanse/arylesterase (P = 0.013), and APOA1 (P = 0.038). A statistical model found that combined measurements of the candidate biomarkers in addition to BNP were capable of correctly predicting heart failure with 83.17% accuracy and an area under the curve (AUC) of 0.90. This was a notable improvement on predictive capacity of BNP measurements alone, which achieved 77.1% accuracy and an AUC of 0.86 (P = 0.005). The protein peptides for LRG1, which contributed most significantly to model performance, were significantly associated with future new onset HF in the non-HF cohort [Peptide 1: odds ratio (OR) 2.345 95% confidence interval (CI) (1.456-3.775) P = 0.000; peptide 2: OR 2.264 95% CI (1.422-3.605), P = 0.001].

CONCLUSIONS

This study has highlighted a number of promising candidate biomarkers for (i) diagnosis of heart failure and subtypes of heart failure and (ii) prediction of future new onset heart failure in patients with cardiovascular risk factors. Furthermore, this study demonstrates that multiplexed measurement of a combined biomarker signature that includes BNP is a more accurate predictor of heart failure than BNP alone.

High-density lipoprotein-mediated cardioprotection in heart failure

The prevalence of heart failure (HF), including reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF), has increased significantly worldwide. However, the prognosis and treatment of HF are still not good. Recent studies have demonstrated that high-density lipoprotein (HDL) plays an important role in cardiac repair during HF. The exact role and mechanism of HDL in the regulation of HF remain unexplained. Here, we discuss recent findings regarding HDL in the progression of HF, such as the regulation of excitation-contraction coupling, energy homeostasis, inflammation, neurohormone activation, and microvascular dysfunction. The effects of HDL on the regulation of cardiac-related cells, such as endothelial cells (ECs), cardiomyocytes (CMs), and on cardiac resident immune cell dysfunction in HF are also explained. An in-depth understanding of HDL function in the heart may provide new strategies for the prevention and treatment of HF.

Biological Consequences of Dysfunctional HDL

Epidemiological studies have suggested an inverse correlation between high-density lipoprotein (HDL) cholesterol levels and the risk of cardiovascular disease. HDLs promote reverse cholesterol transport (RCT) and possess several putative atheroprotective functions, associated to the anti-inflammatory, anti-thrombotic and anti-oxidant properties as well as to the ability to support endothelial physiology. The assumption that increasing HDL-C levels would be beneficial on cardiovascular disease (CVD), however, has been questioned as, in most clinical trials, HDL-C-raising therapies did not result in improved cardiovascular outcomes. These findings, together with the observations from Mendelian randomization studies showing that polymorphisms mainly or solely associated with increased HDL-C levels did not decrease the risk of myocardial infarction, shift the focus from HDL-C levels toward HDL functional properties. Indeed, HDL from atherosclerotic patients not only exhibit impaired atheroprotective functions but also acquire pro-atherogenic properties and are referred to as "dysfunctional" HDL; this occurs even in the presence of normal or elevated HDL-C levels. Pharmacological approaches aimed at restoring HDL functions may therefore impact more significantly on CVD outcome than drugs used so far to increase HDL-C levels. The aim of this review is to discuss the pathological conditions leading to the formation of dysfunctional HDL and their role in atherosclerosis and beyond.

Relationship of High-Density Lipoprotein-Associated Arylesterase Activity to Systolic Heart Failure in Patients with and without Type 2 Diabetes

High-density lipoprotein (HDL) confers protection against cardiovascular disease partly attributable to its robust anti-oxidant activities, which is largely impaired in diabetic conditions. In this study, we analyzed the anti-oxidant activity of HDL, as represented by the arylesterase activity of paraoxonase 1 (PON1) in HDL particles, in 216 consecutive HF patients with (n = 79) or without (n = 137) type 2 diabetes, and age- and gender-matched 112 diabetic and 189 non-diabetic non-HF controls. We found arylesterase activity was significantly decreased in patients with than without HF, and was further decreased when comorbid with diabetes. After adjusting for conventional risk factors and apolipoprotein A-I levels, arylesterase activity remained correlated positively with left ventricular ejection fraction in diabetic (r = 0.325, P = 0.020) but not non-diabetic patients (r = 0.089, P = 0.415), and negatively with NT-proBNP and NYHA functional class in both subgroups. In regression analyses, a higher risk of HF was observed in diabetic than non-diabetic patients when having low arylesterase activities. In conclusion, our data demonstrate that impaired serum arylesterase activity in patients with HF is further reduced when comorbid with diabetes. The relationship of impaired arylesterase activity to HF is especially enhanced in diabetic patients.

Unexpectedly higher diazoxon hydrolysis by serum paraoxonase-1 in coronary heart disease

OBJECTIVES

Low serum PON1 activities (paraoxon, phenyl-acetate or lactone substrates) are associated with coronary heart disease (CHD). We investigated the rate of diazoxon hydrolysis by PON1 in a population with CHD.

DESIGN & METHODS

Case- control study of 410 subjects with CHD and 274 controls. PON1 activity towards paraoxon and diazoxon, PON1 serum concentration and the PON1-55 and 192 polymorphisms were determined.

RESULTS

There were no differences in the distribution of the PON1-55 or PON1-192 genotypes between the CHD and controls, however, PON1 activity towards diazoxon (DIAZ) was significantly (+160%) higher in CHD. In the control population, DIAZ was significantly different between the PON1-192 genotypes in the order QQ > QR > RR (P < .001). However, in CHD the order was QQ > QR = RR. In CHD DIAZ was significantly higher in all the PON1-192 and 55 genotypes compared to controls. In both populations DIAZ was significantly different between the PON1-55 genotypes in the order LL > LM > MM (P < .001).

CONCLUSION

If this result can be replicated in other studies and/or with other PON1 substrates, there may be major diagnostic and mechanistic implications for the relationship of PON1 and CHD.

Exogenous (Pomegranate Juice) or Endogenous (Paraoxonase1) Antioxidants Decrease Triacylglycerol Accumulation in Mouse Cardiovascular Disease-Related Tissues

The polyphenol-rich pomegranate juice (PJ) and the high-density lipoprotein (HDL)-associated paraoxonase1 (PON1) are known as potent atheroprotective antioxidants, but their effects on other tissues related to cardiovascular disease (CVD) remain unknown. The current study aimed to investigate the effects of treating mice with PJ or recombinant PON1 (rePON1) on the oxidation and lipid status of CVD-related tissues: serum, aorta, heart, liver, kidney, visceral, and subcutaneous adipose tissues (VAT and SAT). Both PJ consumption and rePON1 injection decreased the serum levels of thiobarbituric acid-reactive substances (16% and 19%) and triacylglycerols (TAG, 24% and 27%), while only rePON1 increased the levels of thiol groups (35%) and decreased serum cholesterol (15%). Both PJ and rePON1 significantly decreased aortic cholesterol (38% and 32%) and TAG (62% and 58%) contents in association with downregulation of the key TAG biosynthetic enzyme diacylglycerol O-acyltransferase 1 (DGAT1, 71% and 65%), while only PJ decreased aortic lipid peroxides (47%). Substantial TAG-lowering effects of both PJ and rePON1 were observed also in the heart (31% and 42%), liver (34% and 42%), and kidney (42% and 57%). In both VAT and SAT, rePON1 decreased the levels of lipid peroxides (28% and 25%), while PJ decreased the TAG content (22% and 18%). Ex vivo incubation of SAT with serum derived from mice that consumed PJ or injected with rePON1 decreased SAT lipid peroxides (35% or 28%) and TAG mass (12% or 10%). These novel findings highlight potent TAG-lowering properties of exogenous (PJ) and endogenous (PON1) antioxidants in tissues associated with CVD.

Correlation of High-Density Lipoprotein-Associated Paraoxonase 1 Activity With Systemic Inflammation, Disease Activity, and Cardiovascular Risk Factors in Psoriatic Disease

OBJECTIVE

To compare the activity of high-density lipoprotein (HDL)-associated paraoxonase 1 (PON1) in patients with psoriasis (PsO) and patients with psoriatic arthritis (PsA), and to evaluate the association of PON1 activity with the extent of disease activity and severity of the cardiovascular disease (CVD) burden in these patients.

METHODS

Serum levels of paraoxonase and arylesterase activity (both measures of PON1 function in humans) were measured in patients with PsA (n = 198, 51.0% male) and patients with PsO (n = 145, 50.3% male) who were enrolled in a longitudinal psoriatic disease biorepository. Data on PsA disease activity (using the Disease Activity Score in 28 joints [DAS28], Clinical Disease Activity Index, and painful/swollen joint counts), preexistent CVD and CVD risk factors (including diabetes, dyslipidemia, hypertension, and smoking), Framingham Risk Scores for CVD, quality of life measures, and laboratory test findings (erythrocyte sedimentation rate, C-reactive protein level, and lipid profiles) were recorded.

RESULTS

Serum arylesterase activities were significantly lower in patients with PsO and patients with PsA (mean ± SD 111.1 ± 25.5 μmoles/minute/ml and 124.4 ± 33.4 μmoles/minute/ml, respectively) compared to healthy controls (144.3 ± 33.4 μmoles/minute/ml) (each P < 0.001 versus healthy controls). Serum arylesterase activity decreased in parallel with increasing levels of disease activity (DAS28 scores, P = 0.012), older age (P = 0.013), higher body mass index (P = 0.042), greater incidence of metabolic syndrome (P = 0.004) and hypertension (P = 0.014), and worsening Framingham Risk Scores (P = 0.001). However, no correlation was seen between serum arylesterase activity and the extent of disease activity or CVD burden in patients with PsO. Serum paraoxonase activity trended lower both in patients with PsO and in patients with PsA (each P = 0.073 versus healthy controls). However, no association was seen between serum paraoxonase activity and the extent of disease activity or CVD burden in either of the patient cohorts.

CONCLUSION

PON1 activity is decreased in psoriatic diseases. In the PsA cohort, decreases in arylesterase activity correlated with increasing severity of joint disease and CVD burden. Arylesterase activity, as compared to paraoxonase activity, appeared to serve as a more sensitive predictor of preexisting CV risk factors in the PsA cohort. However, this correlation was not observed in the PsO population.

The effect of divalent metal chelators and cadmium on serum phosphotriesterase, lactonase and arylesterase activities of paraoxonase 1

Paraoxonase 1 (PON1) is calcium dependent enzyme involved in many functions in human body. PON1 is synthesized in the liver and secreted to the bloodstream where bounds high-density lipoproteins (HDL). Association of PON1 with HDL increases the enzyme stability and biological activities. PON1 have three different activities: phosphotriesterase, lactonase and arylesterase. Until now there is now commercial available kits to determine these three PON1 activities. Also there is no date about stability of PON1 in serum after storage condition. We have elaborated the optimal conditions for determination of PON1 activities in serum using manual procedure as well as the best storage temperature of human serum for determination of PON1 activities. We have also confirmed that PON1 in serum is associated with HDL. Additionally we have investigated the effect of D-penicillamine, ethylenediaminetetraacetic acid and cadmium chloride on PON1 activities in human serum. D-penicillamine and ethylenediaminetetraacetic acid in therapeutic doses as well as cadmium chloride in toxic doses decrease PON1 activities in human serum when compared to non-treated serum. D-penicillamine as metal chelator inhibits much stronger PON1 activities than ethylenediaminetetraacetic acid.

Proteomic diversity of high-density lipoprotein explains its association with clinical outcome in patients with heart failure

AIMS

Previously, low high-density lipoprotein (HDL) cholesterol was found to be one of the strongest predictors of mortality and/or heart failure (HF) hospitalisation in patients with HF. We therefore performed in-depth investigation of the multifunctional HDL proteome to reveal underlying pathophysiological mechanisms explaining the association between HDL and clinical outcome.

METHODS AND RESULTS

We selected a cohort of 90 HF patients with 1:1 cardiovascular death/survivor ratio from BIOSTAT-CHF. A novel optimised protocol for selective enrichment of lipoproteins was used to prepare plasma. Enriched lipoprotein content of samples was analysed using high resolution nanoscale liquid chromatography-mass spectrometry-based proteomics, utilising a label free approach. Within the HDL proteome, 49 proteins significantly differed between deaths and survivors. An optimised model of 12 proteins predicted death with 76% accuracy (Nagelkerke R² =0.37, P < 0.001). The strongest contributors to this model were filamin-A (related to crosslinking of actin filaments) [odds ratio (OR) 0.31, 95% confidence interval (CI) 0.15-0.61, P = 0.001] and pulmonary surfactant-associated protein B (related to alveolar capillary membrane function) (OR 2.50, 95% CI 1.57-3.98, P < 0.001). The model predicted mortality with an area under the curve of 0.82 (95% CI 0.77-0.87, P < 0.001). Internal cross validation resulted in 73.3 ± 7.2% accuracy.

CONCLUSION

This study shows marked differences in composition of the HDL proteome between HF survivors and deaths. The strongest differences were seen in proteins reflecting crosslinking of actin filaments and alveolar capillary membrane function, posing potential pathophysiological mechanisms underlying the association between HDL and clinical outcome in HF.